The present invention is directed to a low pressure, steady volume manifold suitable to deliver a multi-component working fluid to a high pressure pump for use in oil field operations and the static mixing of multi-component fluids used therein. Fluid components, whether mixed, partially mixed or unmixed, are delivered under low pressure into a core cylindrical tube. Angled cut-out mixing ports allow the fluid to flow to an outer rectangular tube. The combination of the directed flow of the fluid through the angled cut-out ports of the cylindrical tube into the rectangular outer tube, pressure imposed on the fluid and the different geometries in the volume of spacebetween the cylindrical tube and the rectangular tube produce natural turbulent mixing without the use of moving parts to mix the working fluid components.